Abstract. In spite of the significant evolution of spelling and grammar checkers for word-processing software, the problem of judging the appropriateness of language usage in different contexts remains to a large extent still unsolved. This paper presents a novel, argumentative approach to providing proactive assistance for language usage assessment on the basis of the web linguistic corpus. A defeasible argumentation system determines if a given expression is ultimately acceptable by analyzing a defeasible logic program which encodes the user’s preferences. Those expressions assessed as unsuitable are further inspected automatically to help the user make the necessary repairs.